Thursday, March 16, 2023

Internal FDA Report on Smokeless Tobacco Dashes Hopes for Vaping


Kudos to Greg Conley, director of legislative affairs for the American Vapor Manufacturers Association, for making public an internal FDA Center for Tobacco Products (CTP) report, titled, “Summary of Health Effects of Smokeless Tobacco [SLT] Products for Epidemiology Branch Product Application Review.”  Mr. Conley used a Freedom of Information Act request to obtain the 18-page document.

It is important to note the clear acknowledgment by FDA staff that SLT products are safer than cigarettes, illustrated in this executive summary passage:

“Though SLT products are generally considered higher-risk than NRT, they are of considerably lower risk than continued smoking. The overall epidemiological literature supports that cigarette smokers who completely switch to SLT products are likely to substantially lower their risks of cardiovascular disease, lung cancer, and respiratory disease compared to smoking.”

Despite this grudging admission, the report is grossly biased against SLT products. 

First, the authors incorrectly combined all SLT products into one “product class” which includes: “chewing tobacco [chew], [powdered] dry snuff, moist snuff [dip] including snus, nicotine pouch products, and dissolvable products such as lozenges.”  It is hard to believe that the FDA authors cannot distinguish the risks associated with dip and chew products from those of powdered dry snuff, which I have described extensively in the scientific literature (here, here and here). 

Second, the authors cherry-picked those studies that reported higher risks, while they excluded studies that reported no, or lower risks.  This is demonstrated by examining their reference list.

Of the 72 cited studies, dating from 1981 to 2020, they only included those reporting elevated risks among STP users.  More importantly, they excluded two 2019 studies, published by Michael Fisher and colleagues (here), and by my research group (here).  Fisher’s study demonstrated “a clear mortality risk differential between modern SLT products and cigarettes. Cigarette smokers had an increased overall mortality risk and risk for several disease-specific causes of death, while SLT users consistently had lower mortality risks.”  Our study found that STP users “had significant excess mortality from all causes, but not from heart diseases, malignant neoplasms, and all smoking-related diseases.  However, they had higher mortality for all other causes, which was largely seen in age 40–59 years.” [hazard ratios removed]

The most egregious example of cherry-picking involved the FDA staff’s highlighting of elevated mouth cancer risks in the 2016 study by Wyss et al.  I published a letter to the editor about this research, noting that Wyss ignored risk differences between men and women (discussed here and here).  As I wrote:

“The OR [odds ratio] among women ever snuff users (8.89, CI: 3.59, 22.0, based on 20 exposed cases and 12 controls) was an order of magnitude higher than that in men (0.86, CI: 0.49, 1.51, based on 24 exposed cases and 50 controls). 

“The striking difference between women and men reflects completely different snuff exposures.  It is widely known that in the southern U.S. women primarily use powdered dry snuff, whereas men throughout the U.S. use moist snuff.  Powdered dry snuff use is associated with excess oral cancer risk in four previous studies (Reference 2), all of which were cited by Wyss (3, 4, 5, 6).  In contrast, moist snuff is associated with minimal to no risk in eight previous studies (2).

“Wyss and colleagues are knowledgeable about the use of powdered dry snuff by women and its cancer risk; one [Deborah Winn] was first author of a 1981 study reporting that “[t]he relative risk [for oral and pharyngeal cancer] associated with snuff dipping among white [women] nonsmokers [in North Carolina] was 4.2 (95 per cent confidence limits, 2.6 to 6.7).” (4)  Subjects in that study had exclusively used powdered dry snuff.”

The FDA authors concluded: “Complete switching to SLT as a harm reduction alternative to cigarette smoking continues to be an area of active research.”

Despite decades of research demonstrating that SLT use is 98% safer than smoking, FDA staff can only say that smokeless harm reduction is “an area of active research.”  Even if similar differential risk evidence is obtained for vaping, it will never be enough for FDA harm reduction naysayers.



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